Growth in childhood

Question 1

Why is child growth measured?

Answer 1

Normality of growth by age and stage of puberty

Because growth is best indicator of health:-

1. Poor growth in infancy is associated with high childhood morbidity and mortality
2. Identify disorders of growth
3. Assess obesity

Question 2

List what factors are measured for centile charts.

Answer 2

•Centile charts are a way of expressing variation within the population.

–head circumference (skull not fused - circumference shows brain gorwth - ischaemia, hydrocephaly etc.)

–weight

–height/length

–leg length

–BMI

–growth velocity

–specialist charts

Question 3

How do you measure height and plot centile charts?

Answer 3

• Equipment should be accurate and maintained properly
• Position child properly to get accurate height (read instructions on growth chart)
• Remove things that interfere w/measuring - shoes off, hair out of the way
• Calculate age + plot correctly on chart

Question 4

What is the difference between height velocity and cumulative height?

Answer 4

• Cumulative height = how tall child is now (total of all growth from conception)
• Height velocity = how fast a child is growing in cm per year

Question 5

What influences cumulative growth?

Answer 5

1. Events before birth - poor foetal growth, low birth weight, prematurity
2. Medical issues in childhood - malnutrition, chronic disease, endocrine problems inc. GH deficiency
3. Genetic factors - height of family + inherited disorders of growth
4. Randomness - not every child of same parents will be same height; multiple genes randomly distributed at conception influence

Question 6

How do hormones affect growth?

Answer 6

• Hypothalamic GHRH (increases)+ somatostatin (inhibits) GH secretion
• Growth hormone (single chain polypeptide) from anterior pituitary has some growth effect - Pulsatile secretion
• GH stimulates IGF1 release - IGF1 circulates bound to IGF1 binding proteins + stimulates growth in all tissues

Question 7

Describe the phases of growth in children.

Answer 7

• Antenatal - the most rapid phase of growth.
  
  • Maternal health and the placenta are important factors.
• Fastest phase of growth after birth = first 2 years
  
  • Growth Hormone is the most important factor (influence starting from 9-12 months). Nutritionally dependant
  • Rapid initial growth ~23-25 cm in first year
  • Continuation of fetal growth
  • Children move up + down through centiles at this phase
  • Most children move into a centile position by 2/3yrs
• Childhood = Post infancy to adolescence
  
  • GH/IGF-1 axis drives growth. Nutrition less impact
  • Growth rates in boys and girls similar
  • Normal children grow fast enough to keep on same centile thr childhood
  • Presence of growth plates
• Phase of fast growth at puberty (pubertal growth spurt) - timing depends of age at which child enters puberty
  
  • Puberty - sex steroids and GH stimulate the pubertal growth spurt
  • Due to sex steroids, skeleton matures as child grows, epiphyses fuse at end of puberty, growth stops (bone growth plates disappear)
  • The final part of growth occurs in the spine and the final epiphyses to fuse are in the pelvis.

Question 8

What information can be extrapolated from growth centile graphs?

Answer 8

• Centiles are not a “normal range” - you can be taller or shorter than the centile lines and still be completely normal and healthy.
  
  • Most children set out on a centile by about 2 years and grow on the same centile during childhood.
• Pattern of growth is more important than position on the centiles.
  
  • Most very tall or very short people are healthy and grow in a normal pattern.
• A child who falls significantly in centile position is not growing normally, whatever their height.

Question 9

What are the common causes of abnormal growth?

Answer 9

Short stature:

• Genetic
• Pubertal and growth delay
• Poor nutrition
• Chronic paediatric disease (Asthma, Sickle cell, Juvenile chronic arthritis, Inflammatory bowel disease - Crohns/Coeliac, Cystic fibrosis,Renal failure, Congenital heart disease)
  
  • Significant illnesses can interfere with growth, because of inflammation, poor nutrition and the effects of drugs such as steroids.
  • Inflammatory cytokines - stops translation of GH signals to IGF1 (check CRP)
• Endocrine causes
  
  • GH deficiency
  • thyroid hormone deficiency - before 2 - disaster - thyroxine controls brain development)
  • steroid excess
• Genetic disorders affecting bone growth - achondroplasia, Turner’s (X0), Down’s (T21)
• Psychological distress + neglect - higher centres - reduce pulsatility in GH

Tall stature:

• Syndromes of overgrowth - Marfan syndrome, Soto syndrome
• GH excess from pituitary tumour - Precocious puberty
• Tall parents
• Early puberty

Question 10

What are the features of growth of short children?

Answer 10

• Normal growth pattern
• Most short children have a normal growth pattern and do not have any medical problem.
• They are usually the children of short parents
• Not all children with intrauterine growth restriction catch up completely. Growth will be normal in childhood but they have “lost” some height in the antenatal period.

Question 11

What investigations are usually made for children with abnormal growth patterns?

Answer 11

1. full blood count, CRP, serum iron
2. Liver and kidney function
3. thyroid function
4. coeliac screen
5. IGF 1
6. bone age
7. MRI pituitary
8. Pituitary function testing

Question 12

What are the main factors linked to increasing obesity?

Answer 12

• Higher energy intake vs energy expenditure
• In some cultures, overweight has traditionally been seen as a desirable feature indicating wealth + high status
• In different areas, feature of poverty/affluence

Question 13

Why is increasing obesity a concern?

Answer 13

• More likely to get T2DM, cardiovascular disease, some cancers, orthopaedic problems, Polycystic ovarian disease, psychological problems, Cancer, Respiratory difficulties (obstructive apnoea)
• Some ethnic groups have less “tolerance” of obesity - more likely to get complications, e.g. T2DM at lower BMI
  
  • NOTE: BMI is centile in children - 19 obese, 14 - underweight

Question 14

What are causes of childhood obesity?

Answer 14

• Disease: Cushings, Prader Willi, Lawrence-Moon-Biedl
• Genetics of weight - Polygenic inheritance, Weight highly heritable trait (40-70%)
• Mongenic obesity syndromes –rare
  
  • Leptin deficiency
  • Leptin receptor deficiency
  • POMC deficiency
  • PC-1 deficiency
  • MC4R deficiency